Seat Heater Level Does Not Change (Display Changes, But Operation Does Not Change)

Trouble symptom: 

When the seat heater switch is touched, the display on the center information display changes, but the operation mode does not change.

Trouble causes: 

• Seat ventilation Control Module failure
• A/C Control Module failure
• Seat ventilation circuit failure
• Seat heater circuit failure
• Center information display failure
• Cockpit control module failure
• Heater failure

Wiring diagram: 

Seat heater system. Refer to WIRING SYSTEM>Seat Heater System>WIRING DIAGRAM .

Seat ventilation system. Refer to WIRING SYSTEM>Seat Ventilation System>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Read the following DTCs using Subaru Select Monitor. Refer to VENTILATION SEAT (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Refer to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Refer to AIR CONDITIONER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Refer to COCKPIT CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
   • Ventilation Seat
   • Body Control
   • Air Conditioner
   • Cockpit Control

   Are any DTCs displayed?

   Yes  : Perform the diagnosis for the displayed DTCs. Refer to VENTILATION SEAT (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Refer to BODY CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Refer to AIR CONDITIONER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) . Refer to COCKPIT CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   No  : Go to  2.

2. CHECK CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Check malfunctions (terminal bends, connection status, etc.) of the seat ventilation Control Module connector (St41), A/C Control Module connectors (i107) (i108), seat connectors (L57) (R57), coupling connectors (B43) (L51) (R51), and heater connectors (St27) (St28).

   Is the check result OK?

   Yes  : Go to  3.

   No  : Repair the connector.

3. CHECK CAN COMMUNICATION LINE  .

   Inspect LAN system. Refer to LAN SYSTEM (DIAGNOSTICS)>Basic Diagnostic Procedure>PROCEDURE .

   Is the check result OK?

   Yes  : Go to  4.

   No  : Perform the inspection according to the diagnosis for LAN system. Refer to LAN SYSTEM (DIAGNOSTICS)>Basic Diagnostic Procedure>PROCEDURE .

4. CHECK SEAT HEATER  .
   1. Connect all connectors.
   2. Turn the ignition switch to ON.
   3. Start the engine.
   4. Using the Subaru Select Monitor, check the following items in the [Active Test] of [Ventilation Seat]. Refer to VENTILATION SEAT (DIAGNOSTICS)>Active Test .
   • Driver's Seat Heater
   • Passenger's Seat Heater

   Does the seat heater operate properly?

   Yes  : Perform the inspection according to the [Cockpit Control] diagnosis. Refer to COCKPIT CONTROL (DIAGNOSTICS)>Basic Diagnostic Procedure>PROCEDURE .

   No  : Replace the seat ventilation Control Module. Refer to SEATS>SEAT VENTILATION SYSTEM .